In fair weather, the ground may become charged such that there is an electric field just above the surface of the earth, pointing down toward the ground. what is the electric charge of the ground in this situation?

The electric field is defined as the electric force per unit of charge. The direction of the field is taken as the direction of the force it would exert on a positive test load. An electric field is always directed from its positive charge to the negative. Under this condition if the terrestrial electric field is pointing towards the ground, the terminal that is pointing is the negative and that of its surface is the positive. This implies that the sign of the charge of the electric field of the soil will be negative.

15.3 cos 65 degrees trig